Beware the dragon of runaway climate change

Julian Cribb

In news footage of recent tsunamis there are moments when the astonishment of gaping beachgoers and onlookers turns to terror as they finally realise they will be engulfed and are about to die.

We have all seen the same thing in a dozen Hollywood epics: the instant at which fascination resolves into spine-chilling horror as the disaster unfolds. We shudder, thank our lucky stars and return to our airconditioned lives. Thanks to the entertainment industry, society is already well-inoculated with the inability to distinguish real from fictitious catastrophe.

Lately, there has been a lot of media hype over a large hole that opened up in the Siberian tundra. The giant crater, about 70 metres wide and deep, has been widely regarded as a bizarre and rather entertaining geological oddity. The crater is thought to be the result of a gigantic eruption of methane that has lain frozen in the Siberian Arctic for millions of years.

Methane is a gas with 20 to 25 times the climate-forcing potential of carbon dioxide. According to various estimates, there may be as much as 4 trillion tonnes of the stuff locked in permafrost and shallow marine deposits. Reports of its escape into the atmosphere have been growing steadily, ever since a group of students demonstrated the risks by setting fire to venting Arctic gases in 2008.

Taken on its own, the Siberian crater would remain a curiosity rather than an early warning signal of impending planetary disaster, as the Murdoch press had claimed (perhaps in an effort to launch a Trojan horse that climate deniers can exploit).

However, it is not alone. Since it appeared, two more holes have been found. Then, Swedish and Russian scientists sailing through the Siberian Arctic reported that patches of ocean were fizzing like an uncapped soda bottle. For nautical mile after nautical mile, they documented the mass escape of methane, caused when frozen deposits of a gas-water mix on the seabed warm up, collapse and the gas is released.

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"Vast methane plumes were escaping from the sea floor at depths between 500 metres and 150 metres," Orjan Gustafsson, leader of the SWERUS-C3 expedition, said. "At several places, the methane bubbles rose to the ocean surface. Analyses of seawater samples pointed towards levels of dissolved methane 10–50 times higher than normal."

A third pointer is the recording by scientists in Russia, Europe, Canada and Alaska of sharp "spikes" in atmospheric methane levels – far above the current, steadily rising trend. These spikes have been dubbed "dragon's teeth" or "dragon's breath" by their discoverers. They have two possible explanations. They may be errors in the recording equipment – unlikely in view of their frequency – or they represent sudden belches of methane as it escapes from thawing soils and the seabed in the record-breaking heat of this Arctic summer. The scientists are now checking carefully.

Let us be clear: if these methane escapes continue to grow, the risk is they could drive the planet into accelerated or "runaway" global warming. The last time this happened, 50 million years ago, global temperatures rose by an estimated 9 or 10 degrees. In the present context, that would mean the end of the world's food supply, because it would kill all our main food crops and most of our livestock. So this is not a trivial matter, even if the risk of it happening currently appears small.

As American glaciologist Jason Box tweeted: "If even a small fraction of Arctic sea floor carbon is released to the atmosphere, we're f'd." And as another researcher added: "We have absolutely no idea how long we have before the first really big belch, though we've clearly established it's probable in the near future."

In other words climate change may not be some long, slow burn and we have 50 years to trade in our coal and gas-fired power stations and oil-guzzling transport systems. The crisis could arise at any time, without warning. Or not. Nobody knows for sure.

If you want to know what the science says, then a paper in the journal Nature last year summarised it as "an economic timebomb" with a single major methane escape likely to cost the world economy $60 trillion. Scientific debate over the likelihood of such an escape continues, but is firming in favour.

However, like goggling tsunami onlookers, the world's governments and most of its citizens seem oblivious to the magnitude of the risk. People sometimes even complain they "don't want to hear any more bad news", as if not hearing it somehow prevents it from happening.

Australia and its governments are prominent among the gogglers. It has been estimated there is enough coal and gas locked up in the Australian continent to raise the Earth's temperature by 1 degree. Our governments appear eager to release this carbon as quickly as possible, having given the green light to vast new coal and gas extraction projects. They appear not to comprehend the probable consequences for polar melting, methane escape and runaway warming.

This is gambling with the lives of every Australian, indeed every human. If they are right and there is no threat of runaway warming, then taking precautions will only help to slow down man-made climate change and smooth the transition to the clean-energy economy on which much of the world is now embarked. If they are wrong, heaven help us all.

Even if the risk of runaway warming seems remote to some, is it rational to ignore it? If your child could be hit by a truck, would you just leave them on the road and deny the existence of traffic?

The good tidings are that the United States, India and China appear, finally, to have decided to do something about the climate threat and a global action consensus is rapidly building towards the UNFCCC Conference of the Parties in Paris in December. Countries like Germany and Denmark are already decades ahead of us in replacing fossil fuel with renewables.

Australia may eventually be dragged, kicking and whining, into conformity by international outrage from nations with more intelligent and scientifically literate governments. But will it be too late?

Meanwhile, every tonne of coal and gas we dig up and export or burn helps to unleash the dragon's breath. Stoking the risk of runaway climate change is, in reality, now Australia's official national policy.

Julian Cribb is a Canberra science writer and author of The Coming Famine (CSIRO 2010) and Poisoned Planet (A&U 2014).